Status update:
The file worked fine for quite a long time with only one DEM active (the second DEM was still in the file, plugged upstream in series, but its heightfield shader was deactivated). However, upon closing Windows at lunch, then re-opening TG, the file crashes again, giving the same error: "An unknown error occurred in trBucketRender::RenderMore() rasterized pass ht load", and the 3d preview window is completely gray, noting "Aborting Threads". The only thing I can do is end the entire TG application.
During lunch, when I closed down Windows, Windows automatically installed 2017-11 Cumulative Update for Windows 10 Version 1607 (KB4048953). After all the crashes this afternoon, I uninstalled that update, to no further success in TG. Then I tried upgrading to TG 4.1.1.18 but had the same error and crash.
When I used this file two days ago (and even this morning), I added a number of OBJs and population nodes. However, all of them are deactivated and the file still crashes.
I also tried loading .adf heightfields instead of the .flt heightfields (as I had both versions of the same landscape) and TG still crashes.
If I close the 3D preview window while the file is loading the DEMs, TG will load, and then I can manually open the 3D preview window. But if the 3D preview window is open when the DEMs are loading, the file will crash.
Any ideas?
Matt